Why not nitrogen instead of CO2?
One of the trendy things you can spend (waste) your money on in the automotive world is to have your tires pumped up with pure nitrogen. This is supposed to keep your tires inflated longer than regular air, and also supposedly has other benefits.
So I was wondering, since CO2 inflators have the opposite problem (CO2 leaks out faster than air, plus it's a greenhouse gas), why hasn't anyone made a portable nitrogen inflator system for bike tires? Is it purely cost, or is there some technical problem with bottling nitrogen in those little cartridges?